The best ways I have seen are either providing the customer with a Bitcoin address (generate a unique one for each transaction) to send their payment to once they've finalized their order.  Or you can try integrating with a bitcoin wallet service, like MyBitcoin for customers who don't want to bother with downloading the client. 

MyBitcoin set up and integration is known to be kind of a pain from your end, though. 

As another alternative, you could try listing her items on a site that is already set up to accept Bitcoins in the checkout process, for instance *cough* http://bitcoinharbor.com *cough* 

Keep your eyes on bit-pay.com. It's still in testing right now but is going to be a very cool ecommerce solution I think.

It does look great.

Please report when you can accept BTC payments because my GF has some and she doesn't know where to spend them =)

My gf wants that mask, in case you sell it.

Find some info here:

https://mtgox.com/merch/about

but mainly here: https://en.bitcoin.it/wiki/Merchant_Howto

If you want to stick with Wordpress and eShop, you'll have to write (or hire someone to write) a bitcoin payment gateway for eShop, as one doesn't currently exist.  If you're willing to switch to another shopping cart platform, there are various options available.  I've set up OpenCart with the bitcoin payment module, and it seems to work pretty well.